Go to Email.
Select the Email tool from the Tool Menu of your site.
Click the Options link.
Select the default settings.
Choose the desired default settings by selecting the check boxes or radio buttons next to the options you want. These settings will become the default Email tool setting for the entire site.
For example, you may want to check the box for Send me a copy and Add to Email Archive so that they are selected by default. (Individual users may still choose to de-select these two options when sending a message.)
Click Update Defaults.
Click the Update Defaults button to save your changes.